Unusual because populations normally decrease with age
True...
Ball's Pyramid's population is 0.
Another name for population pyramid is Age-Sex graphs.
The population pyramid is a graphical representation of a population's age and gender distribution.
well the country is so small that the population pyramid of the country can be easily made and it will be the most accurate. Unfortunately no one wants its population pyramid in the Vatican city.
The Great Pyramid
A stationary population pyramid is an age-sex pyramid, where the birth rate and death rate are very close throughout all ages.
You can use a POPULATION PYRAMID to help find out the population of a place according to the age, sex, and other demographics.
nuttsacks
It depends on how you cut it. It might be a frustrum, it might be a (somewhat differently shaped) pyramid, or it might be a wedge.
Any face of a tetrahedron can be considered a base. A pyramid, in general, has one polygonal face (with n sides) and n triangular faces. In such a pyramid, the triangular faces would normally not be considered bases - only the n-gon would.